A 75-acre fire has prompted voluntary evacuations of a populated area below the town of Crestline in the San Bernardino Mountains. Fire officials say the fire broke out around 1:30 p.m. Monday afternoon and is 10 percent contained.

The fire is burning a couple of miles below Crestline near Highway 18. As a precaution, authorities have urged — but haven’t ordered — people in the Waterman Canyon area to leave their homes.

None of those houses are threatened, although the fire has forced the temporary shutdown of Highway 18. It’s the most direct route from the Inland region to mountain resort towns.

U.S. Forest Service fire officer Melody Lardner says crews are attacking the fire from the air and the ground.

“We have engines, water tenders and hand crews, air tankers and helicopters on it," Lardner said. "It is steep terrain and it is hot today; temperatures were close to 100 today, but it’s not high wind.”

The Forest Service says the fire could scorch up to 1,000 acres. Its cause is under investigation.

The fire was reported just hours after opening arguments began in the trial of Rickie Lee Fowler, the man suspected of igniting the Old Fire nearly 10 years ago in the San Bernardino Mountains. That wildfire grew to more than 90,000 acres, destroyed hundreds of homes and is believed to have led to the stress-related deaths of five people.

Correction: The headline initially misstated the reason for the evacuation.